H3K27me3 loss indicates an increased risk of recurrence in the Tübingen meningioma cohort

Role of H3K27me3 and Ki-67 Labeling Index in Assessing the Biological Behavior of Meningiomas

BACKGROUND

Meningiomas are neoplasms primarily originating from arachnoid cells and are classified into 3 grades (1, 2, and 3) based on histological features according to the World Health Organization classification. However, this classification system is imperfect especially for grade 1 and 2 meningiomas as many grade 1 tumors recur. Meningiomas are hence a histologically diverse class of tumors exhibiting more unpredictable behavior. Therefore, more improved classification is required, possibly using novel and more dependable biomarkers. In this study, we aim to investigate the role of the H3K27me3 and Ki-67 labeling index (LI) in assessing the biological behavior of meningiomas. The study was conceived, with the primary objective of examining the expression of H3K27me3 and Ki-67 LI in grade 1/2 meningiomas with atypical features to ascertain if this potentially impacts patient prognosis.

METHODS

Upon obtaining clearance from the Institutional Ethical Committee, the authors studied 81 cases of meningiomas including 11 recurrent cases. The study used immunohistochemistry to evaluate the Ki-67 index and H3K27me3 immunohistochemistry. The Ki-67 LI was determined by counting the positively stained MIB-1 cells and categorizing them into <5%, 5%-10%, and >10%. The H3K27me3 staining was evaluated by finding the product of the tumor cells showing positive staining and the intensity of staining. Based on the product of the two, the cases were subdivided into negative (0), low (1-4), and high expression (5-9) of H3K27me3.

RESULTS

The results showed that the presence of atypical morphological features including necrosis and prominent nucleoli in grade 1 meningioma and low expression of H3K27me3 was significantly associated with higher grade, recurrence, and shorter progression-free survival (Kaplan-Meier curves showed higher negative slope). The study also found that a higher Ki-67 LI was associated with recurrence and poor prognosis. This suggests that the H3K27me3 and Ki-67 LI can be useful prognostic markers in meningiomas, particularly in challenging grade 1 and 2 cases and recurrent meningiomas.

CONCLUSIONS

The study highlights the importance of the H3K27me3 and Ki-67 LI in assessing the biological behavior of meningiomas. The findings provide valuable insights into the prognosis and treatment of meningiomas, emphasizing the need for further research to validate these markers and develop targeted therapeutic strategies.

H3K27me3 Loss in Central Nervous System Tumors: Diagnostic, Prognostic, and Therapeutic Implications

Central nervous system (CNS) tumors represent a formidable clinical challenge due to their molecular complexity and varied prognostic outcomes. This review delves into the pivotal role of the epigenetic marker H3K27me3 in the development and treatment of CNS tumors. H3K27me3, specifically the trimethylation of lysine 27 on the histone H3 protein, plays a crucial role in regulating gene expression and maintaining chromatin architecture (e.g., in X-chromosome inactivation). Notably, a reduction in H3K27me3 levels, frequently tied to mutations in the H3 gene family such as H3F3A and HIST1H3B, is evident in diverse brain tumor variants, including the diffuse midline glioma characterized by the H3K27M mutation and certain pediatric high-grade gliomas. The loss of H3K27me3 has been linked to more aggressive behavior in meningiomas, with the trimethylation loss associated with significantly shorter recurrence-free survival (RFS) among grade 2 meningiomas, albeit not within grade 1 tumors. Pediatric posterior fossa ependymomas characterized by a lowered H3K27me3 and DNA hypomethylation exhibit poor prognosis, underscoring the prognostic significance of these epigenetic alterations in CNS tumors. Comprehending the role of H3K27me3 in CNS tumors is vital for advancing diagnostic tools and therapeutic interventions, with the goal of enhancing patient outcomes and quality of life. This review underscores the importance of ongoing investigations into H3K27me to refine and optimize management strategies for CNS tumors, paving the way for improved personalized medicine practices in oncology.

The Role of H3K27me3-Mediated Th17 Differentiation in Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a common chronic progressive inflammatory autoimmune disease. T helper 17 (Th17) cells are the major effector cells mediating AS inflammation. Histone 3 Lys 27 trimethylation (H3K27me3) is an inhibitory histone modification that silences gene transcription and plays an important role in Th17 differentiation. The objective of this study was to investigate the expression of H3K27me3 in patients with AS and to explore its epigenetic regulation mechanism of Th17 differentiation during AS inflammation. We collected serum samples from 45 patients with AS at various stages and 10 healthy controls to measure their Interleukin-17 (IL-17) levels using ELISA. A quantitative polymerase chain reaction was used to quantify the mRNA levels of RORc and the signaling molecules of the JAK2/STAT3 pathway, JMJD3, and EZH2. Additionally, Western blot analysis was performed to quantify the protein levels of H3K27me3, RORγt, JAK2, STAT3, JMJD3, and EZH2 in cell protein extracts. The results showed that H3K27me3 expression in peripheral blood mononuclear cells (PBMCs) was significantly lower in patients with active AS compared to both the normal control groups and those with stable AS. Moreover, a significant negative correlation was observed between H3K27me3 expression and the characteristic transcription factor of Th17 differentiation, RORγt. We also discovered that patients with active AS exhibited significantly higher levels of JMJD3, an inhibitor of H3K27 demethylase, compared to the normal control group and patients with stable AS, while the expression of H3K27 methyltransferase (EZH2) was significantly lower. These findings suggest that H3K27me3 may be a dynamic and important epigenetic modification in AS inflammation, and JMJD3/EZH2 regulates the methylation level of H3K27me3, which may be one of the key regulatory factors in the pathogenesis of AS. These findings contribute to our understanding of the role of epigenetics in AS and may have implications for the development of novel therapeutic strategies for AS.

The Impact of Molecular and Genetic Analysis on the Treatment of Patients with Atypical Meningiomas

Meningiomas represent approximately 40% of all primary tumors of the central nervous system (CNS) and, based on the latest World Health Organization (WHO) guidelines, are classified into three grades and fifteen subtypes. The optimal treatment comprises gross total tumor resection. The WHO grade and the extent of tumor resection assessed by the Simpson grading system are the most important predictors of recurrence. Atypical meningiomas, a grade 2 meningioma, which represent almost a fifth of all meningiomas, have a recurrence rate of around 50%. Currently, different histopathologic, cytogenetic, and molecular genetic alterations have been associated with different meningioma phenotypes; however, the data are insufficient to enable the development of specific treatment plans. The optimal treatment, in terms of adjuvant radiotherapy and postoperative systemic therapy in atypical meningiomas, remains controversial, with inconclusive evidence in the literature and existing studies. We review the recent literature to identify studies investigating relevant atypical meningioma biomarkers and their clinical application and effects on treatment options.

Evaluation of prognostic biomarkers in meningiomas and their clinical implications in settings with limited resources

Background

The 5th edition of the World Health Organization (WHO) Central Nervous System (CNS) tumor classification for meningiomas acknowledges the clinical relevance of genomic profiling studies and emphasizes the importance of incorporating molecular information alongside histopathological features, leading to more accurate diagnoses and improved patient care.

Methods

We analyzed 206 meningioma samples (108 histological grade 1, 89 grade 2, and 9 grade 3) to study pTERT mutations, CDKN2A/B homozygous deletion, loss of H3K27me3, and p16 expression. The association of these molecular markers with survival outcomes was also assessed.

Results

pTERT mutation was found in 4.85% of cases, predominantly occurring in histological grade 2 (11.24%), while none of the histological grade 1 or 3 meningiomas exhibited this mutation. CDKN2A/B gene deletion was absent in grade 1 and detected in 2.24% of grade2, and 33.3% of histological grade 3 cases. There was a significant increase in loss of H3K27me3 with higher tumor grades, while p16 loss was observed in over 50% of cases across all histological grades. The presence of pTERT mutation and CDKN2A/B homozygous deletion resulted in the reclassification of 5.33% (11/206) of meningiomas as integrated grade 3. pTERT mutation and CDKN2A/B deletion, emerged as prognostically relevant markers, showing significant differences in progression-free survival (PFS) between integrated grade 3 and histological grade 2 meningiomas (P = .0002).

Conclusions

pTERT mutations are the most clinically relevant genetic alterations in meningiomas. Routine testing for pTERT mutations can identify high-risk cases of histologically grade 2 meningiomas, providing crucial prognostic information for treatment planning. CDKN2A/B alteration is rare and not cost-effective in assessing meningiomas. Immunohistochemical assessment of p16 and H3K27me3 expression lacks significant prognostic value. Assessment of pTERT mutations offers a cost-effective and valuable diagnostic tool for meningiomas.

Prognostic Factors and Outcomes in World Health Organization Grade 1 and Grade 2 Intracranial Meningiomas-5-Year Institutional Experience

BACKGROUND

Meningiomas are the most frequent primary intracranial tumor. While histological grade and grade of excision are established predictors of recurrence, the predictive ability of other clinical features, such as the role of radical excision of dural attachment and postoperative radiation therapy in intermediate-risk groups, remains unknown.

METHODS

Clinical and radiological features and surgical details were analyzed in 451 World Health Organization (WHO) grade 1 intracranial meningiomas and 248 WHO grade 2 meningiomas operated on between 2010 and 2015. Outcomes were assessed in 352 WHO grade 1 and 208 WHO grade 2 meningiomas, studying the effect of extent of resection and use of radiation therapy. Kaplan-Meier analysis was used to determine differences in survival by extent of resection and use of postoperative radiation therapy in the treatment of the meningiomas.

RESULTS

The mean age of the cohort was 46.3 years, with a female predominance. On univariate analysis, sex, WHO grade, and Simpson grade were significant predictors of recurrence. On multivariate analysis, WHO grade and Simpson grade remained significant predictors of recurrence. Recurrence was significantly associated with poor performance status and mortality. Postoperative radiation significantly improved progression-free survival among patients with grade 2 meningiomas who underwent gross total resection, but not among patients with grade 1 and grade 2 meningiomas who underwent subtotal resection.

CONCLUSIONS

WHO grade and Simpson grade are independent predictors of recurrence in meningiomas. Regardless of WHO grade, gross total resection must be performed when possible, and postoperative radiation therapy may be recommended in grade 2 meningiomas.

Biomarkers for prognosis of meningioma patients: A systematic review and meta-analysis

Meningioma is the most common primary brain tumor and many studies have evaluated numerous biomarkers for their prognostic value, often with inconsistent results. Currently, no reliable biomarkers are available to predict the survival, recurrence, and progression of meningioma patients in clinical practice. This study aims to evaluate the prognostic value of immunohistochemistry-based (IHC) biomarkers of meningioma patients. A systematic literature search was conducted up to November 2023 on PubMed, CENTRAL, CINAHL Plus, and Scopus databases. Two authors independently reviewed the identified relevant studies, extracted data, and assessed the risk of bias of the studies included. Meta-analyses were performed with the hazard ratio (HR) and 95% confidence interval (CI) of overall survival (OS), recurrence-free survival (RFS), and progression-free survival (PFS). The risk of bias in the included studies was evaluated using the Quality in Prognosis Studies (QUIPS) tool. A total of 100 studies with 16,745 patients were included in this review. As the promising markers to predict OS of meningioma patients, Ki-67/MIB-1 (HR = 1.03, 95%CI 1.02 to 1.05) was identified to associate with poor prognosis of the patients. Overexpression of cyclin A (HR = 4.91, 95%CI 1.38 to 17.44), topoisomerase II α (TOP2A) (HR = 4.90, 95%CI 2.96 to 8.12), p53 (HR = 2.40, 95%CI 1.73 to 3.34), vascular endothelial growth factor (VEGF) (HR = 1.61, 95%CI 1.36 to 1.90), and Ki-67 (HR = 1.33, 95%CI 1.21 to 1.46), were identified also as unfavorable prognostic biomarkers for poor RFS of meningioma patients. Conversely, positive progesterone receptor (PR) and p21 staining were associated with longer RFS and are considered biomarkers of favorable prognosis of meningioma patients (HR = 0.60, 95% CI 0.41 to 0.88 and HR = 1.89, 95%CI 1.11 to 3.20). Additionally, high expression of Ki-67 was identified as a prognosis biomarker for poor PFS of meningioma patients (HR = 1.02, 95%CI 1.00 to 1.04). Although only in single studies, KPNA2, CDK6, Cox-2, MCM7 and PCNA are proposed as additional markers with high expression that are related with poor prognosis of meningioma patients. In conclusion, the results of the meta-analysis demonstrated that PR, cyclin A, TOP2A, p21, p53, VEGF and Ki-67 are either positively or negatively associated with survival of meningioma patients and might be useful biomarkers to assess the prognosis.

Predicting meningioma grades and pathologic marker expression via deep learning

OBJECTIVES

To establish a deep learning (DL) model for predicting tumor grades and expression of pathologic markers of meningioma.

METHODS

A total of 1192 meningioma patients from two centers who underwent surgical resection between September 2018 and December 2021 were retrospectively included. The pathological data and post-contrast T1-weight images for each patient were collected. The patients from institute I were subdivided into training, validation, and testing sets, while the patients from institute II served as the external testing cohort. The fine-tuned ResNet50 model based on transfer learning was adopted to classify WHO grade in the whole cohort and predict Ki-67 index, H3K27me3, and progesterone receptor (PR) status of grade 1 meningiomas. The predictive performance was evaluated by the accuracy and loss curve, confusion matrix, receiver operating characteristic curve (ROC), and area under curve (AUC).

RESULTS

The DL prediction model for each label achieved high predictive performance in two cohorts. For WHO grade prediction, the area under the curve (AUC) was 0.966 (95%CI 0.957-0.975) in the internal testing set and 0.669 (95%CI 0.643-0.695) in the external validation cohort. The AUC in predicting Ki-67 index, H3K27me3, and PR status were 0.905 (95%CI 0.895-0.915), 0.773 (95%CI 0.760-0.786), and 0.771 (95%CI 0.750-0.792) in the internal testing set and 0.591 (95%CI 0.562-0.620), 0.658 (95%CI 0.648-0.668), and 0.703 (95%CI 0.674-0.732) in the external validation cohort, respectively.

CONCLUSION

DL models can preoperatively predict meningioma grades and pathologic marker expression with favorable predictive performance.

CLINICAL RELEVANCE STATEMENT

Our DL model could predict meningioma grades and expression of pathologic markers and identify high-risk patients with WHO grade 1 meningioma, which would suggest a more aggressive operative intervention preoperatively and a more frequent follow-up schedule postoperatively.

KEY POINTS

WHO grades and some pathologic markers of meningioma were associated with therapeutic strategies and clinical outcomes. A deep learning-based approach was employed to develop a model for predicting meningioma grades and the expression of pathologic markers. Preoperative prediction of meningioma grades and the expression of pathologic markers was beneficial for clinical decision-making.

Inhibition of BMP signaling pathway induced senescence and calcification in anaplastic meningioma

PURPOSE

Meningiomas are the most common type of brain tumors and are generally benign, but malignant atypical meningiomas and anaplastic meningiomas frequently recur with poor prognosis. The metabolism of meningiomas is little known, so few effective treatment options other than surgery and radiation are available, and the targets for treatment of recurrence are not well defined. The Aim of this paper is to find the therapeutic target.

METHODS

The effects of bone morphogenetic protein (BMP) signal inhibitor (K02288) and upstream regulator Gremlin2 (GREM2) on meningioma's growth and senescence were examined. In brief, we examined as follows: 1) Proliferation assay by inhibiting BMP signaling. 2) Comprehensive analysis of forced expression GREM2.3) Correlation between GREM2 mRNA expression and proliferation marker in 87 of our clinical samples. 4) Enrichment analysis between GREM2 high/low expressed groups using RNA-seq data (42 cases) from the public database GREIN. 5) Changes in metabolites and senescence markers associated with BMP signal suppression.

RESULTS

Inhibitors of BMP receptor (BMPR1A) and forced expression of GREM2 shifted tryptophan metabolism from kynurenine/quinolinic acid production to serotonin production in malignant meningiomas, reduced NAD + /NADH production, decreased gene cluster expression involved in oxidative phosphorylation, and caused decrease in ATP. Finally, malignant meningiomas underwent cellular senescence, decreased proliferation, and eventually formed psammoma bodies. Reanalyzed RNA-seq data of clinical samples obtained from GREIN showed that increased expression of GREM2 decreased the expression of genes involved in oxidative phosphorylation, similar to our experimental results.

CONCLUSIONS

The GREM2-BMPR1A-tryptophan metabolic pathway in meningiomas is a potential new therapeutic target.

Atypical meningioma: Histopathological, genetic, and epigenetic features to predict recurrence risk

Grading assessed according to World Health Organization (WHO) criteria is a major prognostic factor for determining the risk of recurrence in patients with meningiomas and establishing the most appropriate therapeutic strategy after surgery. However, the main issue is to predict the recurrence risk of WHO grade 2 meningioma and, more specifically, of the atypical subtype. Indeed, owing to a reported recurrence rate of 50%, either radiotherapy or observation is currently considered an option after gross total surgical resection of atypical meningiomas. These heterogeneous clinical outcomes are likely related to the broad histopathological diagnostic criteria for this subtype, and whether meningiomas only present as brain invasion should be classified as atypical remains controversial. Over the last few years, several studies have shown that DNA methylation profiling, next-generation sequencing, and transcriptomics can better stratify meningiomas for their recurrence risk than histology. The main limitations to the widespread use of these approaches to classify meningiomas are their high cost and the need for sophisticated technologies. However, all studies concurred that atypical meningiomas without chromosome 1p deletion display a low recurrence risk, suggesting that the assessment of this cytogenetic alteration could represent an easy and quick method to determine which patients could benefit from adjuvant treatment after surgery. In addition, prognostically unfavorable molecular groups can be distinguished using specific immunostainings, although further validation is required.

Hotspots and Trends in Meningioma Research Based on Bibliometrics, 2011-2021

BACKGROUND

Meningiomas, the most prevalent benign intracranial neoplasms, have been studied extensively for many years, but significant problems remain. To date, there is a scarcity of detailed studies elucidating the hotspots and future directions of meningiomas research.

METHODS

A comprehensive search and screening strategy was used to collect relevant studies published between 2011 and 2021 in the Web of Science Core Collection database. Thorough and systematic coauthorship and co-occurrence keyword maps were generated, and tables of statistics summarizing countries, organizations, authors, and keywords were created.

RESULTS

A total of 1544 articles meeting the screening criteria were collected. The countries producing the most publications between 2011 and 2021 were the United States, Germany, and China, with 586, 244, and 197 records, repectively. The cooperation networks also revolved mainly around these 3 countries, particularly the United States. The most frequently used keyword was "surgery," followed by "recurrence" and "management," with the frequencies of 248, 212, and 163, respectively. The most prominent cluster during the last decade was the #0 methylation cluster, and several keywords, including "survival," "brain invasion," and "magnetic resonance imaging," exhibited significant burst strength.

CONCLUSIONS

This study aimed to provide a comprehensive analysis of the research landscape and to identify potential research directions. Our findings disclose productive individuals and institutions. The current research focuses on the molecular pathology of meningiomas, improvements in techniques, and advances in diagnosis by magnetic resonance imaging. In particular, the improvements in molecular pathology might direct future research directions.

A machine learning-based integrated clinical model for predicting prognosis in atypical meningioma patients

PURPOSE

Atypical meningioma (AM) recurs in up to half of patients after surgical resection and may require adjuvant therapy to improve patient prognosis. Various clinicopathological features have been shown to have prognostic implications in AM, but an integrated prediction model is lacking. Thus, in this study, we aimed to develop and validate an integrated prognostic model for AM.

METHODS

A retrospective cohort of 528 adult AM patients surgically treated at our institution were randomly assigned to a training or validation group in a 7:3 ratio. Sixteen baseline demographic, clinical, and pathological parameters, progression-free survival (PFS), and overall survival (OS) were analysed. Sixty-five combinations of machine learning (ML) algorithms were used for model training and validation to predict tumour recurrence and patient mortality.

RESULTS

The random survival forest (RSF) model was the best model for predicting recurrence and death. Primary or secondary tumour, Ki-67 index, extent of resection, tumour size, brain involvement, tumour necrosis, and age contributed significantly to the model. The C-index value of the RSF recurrence prediction model reached 0.8080. The AUCs for 1-, 3-, and 5-year PFS were 0.83, 0.82, and 0.86, respectively. The C-index value of the RSF death prediction model reached 0.8890. The AUCs for 3-year and 5-year OS were 0.88 and 0.89, respectively.

CONCLUSION

A high-performing integrated RSF predictive model for AM recurrence and patient mortality was proposed that may guide therapeutic decision-making and long-term monitoring.

High-Throughput Screening of Epigenetic Inhibitors in Meningiomas Identifies HDAC, G9a, and Jumonji-Domain Inhibition as Potential Therapies

Background  Epigenetics may predict treatment sensitivity and clinical course for patients with meningiomas more accurately than histopathology. Nonetheless, targeting epigenetic mechanisms is understudied for pharmacotherapeutic development for these tumors. The bio-molecular insights and potential therapeutic development of meningioma epigenetics led us to investigate epigenetic inhibition in meningiomas. Methods  We screened a 43-tumor cohort using a 139-compound epigenetic inhibitor library to assess sensitivity of relevant meningioma subgroups to epigenetic inhibition. The cohort was composed of 5 cell lines and 38 tumors cultured directly from surgery; mean patient age was 56.6 years ± 13.9 standard deviation. Tumor categories: 38 primary tumors, 5 recurrent; 33 from females, 10 from males; 32 = grade 1; 10 = grade 2; 1 = grade 3. Results  Consistent with our previous results, histone deacetylase inhibitors (HDACi) were the most efficacious class. Panobinostat significantly reduced cell viability in 36 of 43 tumors; 41 tumors had significant sensitivity to some HDACi. G9a inhibition and Jumonji-domain inhibition also significantly reduced cell viability across the cohort; tumors that lost sensitivity to panobinostat maintained sensitivity to either G9a or Jumonji-domain inhibition. Sensitivity to G9a and HDAC inhibition increased with tumor grade; tumor responses did not separate by gender. Few differences were found between recurrent and primary tumors, or between those with prior radiation versus those without. Conclusions  Few efforts have investigated the efficacy of targeting epigenetic mechanisms to treat meningiomas, making the clinical utility of epigenetic inhibition largely unknown. Our results suggest that epigenetic inhibition is a targetable area for meningioma pharmacotherapy.

Impact of H3K27 trimethylation loss in meningiomas: a meta-analysis

Trimethylation of lysine 27 on histone 3 (H3K27me3) loss has been implicated in worse prognoses for patients with meningiomas. However, there have been challenges in measuring H3K27me3 loss, quantifying its impact, and interpreting its clinical utility. We conducted a systematic review across Pubmed, Embase, and Web of Science to identify studies examining H3K27me3 loss in meningioma. Clinical, histopathological, and immunohistochemistry (IHC) characteristics were aggregated. A meta-analysis was performed using a random-effects model to assess prevalence of H3K27me3 loss and meningioma recurrence risk. Study bias was characterized using the NIH Quality Assessment Tool and funnel plots. Nine publications met inclusion criteria with a total of 2376 meningioma cases. The prevalence of H3K27me3 loss was 16% (95% CI 0.09-0.27), with higher grade tumors associated with a significantly greater proportion of loss. H3K27me3 loss was more common in patients who were male, had recurrent meningiomas, or required adjuvant radiation therapy. Patients were 1.70 times more likely to have tumor recurrence with H3K27me3 loss (95% CI 1.35-2.15). The prevalence of H3K27me3 loss in WHO grade 2 and 3 meningiomas was found to be significantly greater in tissue samples less than five years old versus tissue of all ages and when a broader definition of IHC staining loss was applied. This analysis demonstrates that H3K27me3 loss significantly associates with more aggressive meningiomas. While differences in IHC and tumor tissue age have led to heterogeneity in studying H3K27me3 loss, a robust prognostic signal is present. Our findings suggest an opportunity to improve study design and standardize tissue processing to optimize clinical viability of this epigenetic marker.

Medical Management of Meningiomas

Meningiomas represent the most common type of benign tumor of the extra-axial compartment. Although most meningiomas are benign World Health Organization (WHO) grade 1 lesions, the increasingly prevalent of WHO grade 2 lesion and occasional grade 3 lesions show worsened recurrence rates and morbidity. Multiple medical treatments have been evaluated but show limited efficacy. We review the status of medical management in meningiomas, highlighting successes and failures of various treatment options. We also explore newer studies evaluating the use of immunotherapy in management.

Advances in the systemic therapy for recurrent meningiomas and the challenges ahead

INTRODUCTION

Meningiomas represent the most common primary neoplasms of the central nervous system (CNS). 20% present with atypical (WHO grade II) or malignant (grade III) meningiomas, which show aggressive biologic behavior and high recurrence. Although surgical resection and radiation therapy are the primary treatment options for these tumors, there is a subgroup of patients who do not respond well to or are poor candidates for these approaches, leading to the exploration of systemic therapies as an alternative.

AREAS COVERED

The literature on different therapeutic groups of systemic drugs for recurrent meningiomas is reviewed, with a focus on the different molecular targets. Past and current ongoing clinical trials are also discussed.

EXPERT OPINION

To date, there is no recognized treatment that has demonstrated a substantial increase in progression-free or overall survival rates. Nonetheless, therapies targeting anti-VEGF have exhibited more encouraging results in general. The examination of genomic and epigenomic traits of meningiomas, along with the integration of molecular markers into the latest WHO tumor grading system, has provided valuable insights. This has opened avenues for exploring numerous intracellular and extracellular pathways, as well as mutations, that have been targeted in ongoing clinical trials.

Review of meningioma diagnosis and management

Meningiomas are the most common intracranial tumors in adult patients. Although the majority of meningiomas are diagnosed as benign, approximately 20% of cases are high-grade tumors that require significant clinical treatment. The gold standard for grading central nervous system tumors comes from the World Health Organization Classification of Tumors of the central nervous system. Treatment options also depend on the location, imaging, and histopathological features of the tumor. This review will cover diagnostic strategies for meningiomas, including 2021 updates to the World Health Organization's grading of meningiomas. Meningioma treatment plans are variable and highly dependent on tumor grading. This review will also update the reader on developments in the treatment of meningiomas, including surgery, radiation therapy and monoclonal antibody treatment.

Recent advances in the molecular prognostication of meningiomas

Meningiomas are the most common primary intracranial neoplasm. While traditionally viewed as benign, meningiomas are associated with significant patient morbidity, and certain meningioma subgroups display more aggressive and malignant behavior with higher rates of recurrence. Historically, the risk stratification of meningioma recurrence has been primarily associated with the World Health Organization histopathological grade and surgical extent of resection. However, a growing body of literature has highlighted the value of utilizing molecular characteristics to assess meningioma aggressiveness and recurrence risk. In this review, we discuss preclinical and clinical evidence surrounding the use of molecular classification schemes for meningioma prognostication. We also highlight how molecular data may inform meningioma treatment strategies and future directions.

Genomic markers of recurrence risk in atypical meningioma following gross total resection

Background

Meningiomas are the most common primary central nervous system (CNS) tumor in adults and CNS World Health Organization grade 2 (atypical) meningiomas show an intermediate risk of recurrence/progression. Molecular parameters are needed to better inform management following gross total resection (GTR).

Methods

We performed comprehensive genomic analysis of tumor tissue from 63 patients who underwent radiologically confirmed GTR of a primary grade 2 meningioma, including a CLIA-certified target next-generation sequencing panel (n = 61), chromosomal microarray (n = 63), genome-wide methylation profiling (n = 62), H3K27me3 immunohistochemistry (n = 62), and RNA-sequencing (n = 19). Genomic features were correlated with long-term clinical outcomes (median follow-up: 10 years) using Cox proportional hazards regression modeling and published molecular prognostic signatures were evaluated.

Results

The presence of specific copy number variants (CNVs), including -1p, -10q, -7p, and -4p, was the strongest predictor of decreased recurrence-free survival (RFS) within our cohort (P < .05). NF2 mutations were frequent (51%) but did not show a significant association with RFS. DNA methylation-based classification assigned tumors to DKFZ Heidelberg benign (52%) or intermediate (47%) meningioma subclasses and was not associated with RFS. H3K27 trimethylation (H3K27me3) was unequivocally lost in 4 tumors, insufficient for RFS analysis. Application of published integrated histologic/molecular grading systems did not improve prediction of recurrence risk over the presence of -1p or -10q alone.

Conclusions

CNVs are strong predictors of RFS in grade 2 meningiomas following GTR. Our study supports incorporation of CNV profiling into clinical evaluation to better guide postoperative patient management, which can be readily implemented using existing, clinically validated technologies.

Loss of H3K27me3 expression enriches in recurrent grade 1&2 meningiomas and maintains as a biomarker stratifying progression risk

PURPOSE

To determine if loss of H3K27me3 could predict higher risk of re-recurrence in recurrent meningiomas.

METHODS

A retrospective, single-center cohort study was performed for patients who underwent resection of recurrent grade 1 (N = 132) &2 (N = 32) meningiomas from 2009 to 2013. Association of H3K27me3 staining and clinical parameters was analyzed. Additionally, H3K27me3 staining was performed from 45 patients whose tumors recurred and were resected during the follow-up, to evaluate H3K27me3 change during tumor progression. Survival analysis was performed as well.

RESULTS

Loss of H3K27me3 expression was observed in 83 patients, comprising 63 grade 1 (47.7%) and 20 grade 2 patients (62.5%). Both grade 1 (p < 0.001) and grade 2 recurrent meningiomas (p < 0.001) had a higher frequency of H3K27me3 loss, compared to de novo meningiomas. 8 of 27 tumors with retained H3K27me3 lost H3K27me3 during re-recurrence (29.6%), while no gain of H3K27me3 was observed in progressive disease from 18 tumors with H3K27me3 loss. Loss of H3K27me3 expression was associated with an earlier re-recurrence in recurrent meningiomas grade 1 and 2 (p < 0.001), and was an independent prognostic factor for PFS in recurrent grade 1 meningiomas (p = 0.005).

CONCLUSION

Compared to primary meningiomas, recurrent meningiomas more predominantly had loss of H3K27me3 expression, and further loss can occur during the progression of recurrent tumors. Our results further demonstrated that loss of H3K27me3 predicted shorter PFS in recurrent grade 1 and grade 2 meningiomas. Our work thus supports clinical testing of H3K27me3 in recurrent meningiomas WHO grade 1 and 2.

Histone H3 K27 alterations in central nervous system tumours: Challenges and alternative diagnostic approaches

Upon the discovery of frequent oncogenic histone alterations in paediatric diffuse high-grade gliomas, the epigenetic and transcriptional landscapes of tumours have become increasingly important aspects of diagnostic and prognostic analysis. The replacement of lysine 27 with methionine in H3 histone variants - H3 p.K28M (K27M) - was the first reported histone mutation associated with human malignancies, seen in up to 80% of paediatric diffuse midline gliomas. This discovery contributed to the updated 2021 World Health Organization (WHO) classification of central nervous system (CNS) tumours in which paediatric diffuse high-grade gliomas were classified into molecular-based categories. Therefore, molecular analysis of tumour cells has become increasingly necessary for determining disease prognosis and potential therapeutic strategies. Although detection of histone alterations is crucial for the diagnosis of specific glioma subtypes, several studies have identified them in other CNS tumours, which may be misleading during routine diagnostic work. While traditional biopsies remain the standard for diagnosis of gliomas, they pose a high risk for surgical complications and patient morbidity. Consequently, this review highlights the importance of the H3 K27-alterations in paediatric gliomas and several other CNS tumours. We also discuss the potential of liquid biopsies as a minimally invasive and highly effective alternative for confirming the diagnosis and potential targeted epigenetic therapies which may improve the survival of patients.

H3K27me3 in Diffuse Midline Glioma and Epithelial Ovarian Cancer: Opposing Epigenetic Changes Leading to the Same Poor Outcomes

Histone post-translational modifications modulate gene expression through epigenetic gene regulation. The core histone H3 family members, H3.1, H3.2, and H3.3, play a central role in epigenetics. H3 histones can acquire many post-translational modifications, including the trimethylation of H3K27 (H3K27me3), which represses transcription. Triple methylation of H3K27 is performed by the histone methyltransferase Enhancer of Zeste Homologue 2 (EZH2), a component of the Polycomb Repressive Complex 2. Both global increases and decreases in H3K27me3 have been implicated in a wide range of cancer types. Here, we explore how opposing changes in H3K27me3 contribute to cancer by highlighting its role in two vastly different cancer types; (1) a form of glioma known as diffuse midline glioma H3K27-altered and (2) epithelial ovarian cancer. These two cancers vary widely in the age of onset, sex, associated mutations, and cell and organ type. However, both diffuse midline glioma and ovarian cancer have dysregulation of H3K27 methylation, triggering changes to the cancer cell transcriptome. In diffuse midline glioma, the loss of H3K27 methylation is a primary driving factor in tumorigenesis that promotes glial cell stemness and silences tumor suppressor genes. Conversely, hypermethylation of H3K27 occurs in late-stage epithelial ovarian cancer, which promotes tumor vascularization and tumor cell migration. By using each cancer type as a case study, this review emphasizes the importance of H3K27me3 in cancer while demonstrating that the mechanisms of histone H3 modification and subsequent gene expression changes are not a one-size-fits-all across cancer types.

Molecular landscapes of longitudinal NF2/22q and non-NF2/22q meningiomas show different life histories

Recurrence is a major complication of some meningiomas. Although there were many studies on biomarkers associated with higher grades or increased aggressiveness, few studies specifically examined longitudinal samples of primary meningiomas and recurrences from the same patients for molecular life history. We studied 99 primary and recurrent meningiomas from 42 patients by FISH for 22q, 1q, 1p, 3p, 5q, 6q, 10p, 10q, 14q, 18q, CDKN2A/B homozygous deletion, ALT (Alternative Lengthening of Telomere), TERT re-arrangement, targeted sequencing and TERTp sequencing. Although NF2 mutation and 22q were well known to be aetiological events in meningiomas, we found that in these paired meningiomas, combining the two events resulted in an NF2/22q group (57 tumors from 25 patients) which were almost mutually exclusive with those cases without these two changes (42 tumors from 17 patients) for NF2/22q. No other molecular changes were totally unique to NF2/22q or non-NF2/22q tumors. For molecular evolution, NF2/22q meningiomas had higher cytogenetic abnormalities than non-NF2/22q meningiomas (p = 0.003). Most of the cytogenetic changes in NF2/22q meningiomas were present from the outset whereas for non-NF2/22q meningiomas, cytogenetic events were uncommon in the primary tumors and most were acquired in recurrences. For non-NF2/22q tumors, CDKN2A/B homozygous deletion, 1q gain, 18p loss, 3p loss, and ALT were preferentially found in recurrences. Mutations were largely conserved between primary and recurrent tumors. Phylogenetic trees showed 11/11 patients with multiple recurrent tumors had a conserved evolutionary pattern. We conclude that for molecular life history, NF2 and 22q should be regarded as a group. NF2/22q recurring meningiomas showed more cytogenetic abnormalities in the primary tumors, whereas non-NF2/22q meningiomas showed CDKN2A/B deletion and other cytogenetic abnormalities and ALT at recurrences. Although chromosome 1p loss is a known poor prognostic marker in meningiomas, it was also associated with a shorter TBR (time between resection) in this cohort (p = 0.002).

Advances in Molecular Biological and Translational Studies in World Health Organization Grades 2 and 3 Meningiomas: A Literature Review

The treatment of World Health Organization (WHO) grades 2 and 3 meningiomas remains difficult and controversial. The pathogenesis of high-grade meningiomas was expected to be elucidated to improve treatment strategies. The molecular biology of meningiomas has been clarified in recent years. High-grade meningiomas have been linked to NF2 mutations and 22q deletion. CDKN2A/B homozygous deletion and TERT promoter mutations are independent prognostic factors for WHO grade 3 meningiomas. In addition to 22q loss, 1p, 14p, and 9q loss have been linked to high-grade meningiomas. Meningiomas enriched in copy number alterations may be biologically invasive. Furthermore, several new comprehensive classifications of meningiomas have been proposed based on these molecular biological features, including DNA methylation status. The new classifications may have implications for treatment strategies for refractory aggressive meningiomas because they provide a more accurate prognosis compared to the conventional WHO classification. Although several systemic therapies, including molecular targeted therapies, may be effective in treating refractory aggressive meningiomas, these drugs are being tested. Systemic drug therapy for meningioma is expected to be developed in the future. Thus, this review aims to discuss the distinct genomic alterations observed in WHO grade 2 and 3 meningiomas, as well as their diagnostic and therapeutic implications and systemic drug therapies for high-grade meningiomas.

The prognostic role of the immunohistochemical expression of S100 in meningiomas

BACKGROUND

Despite best clinical management, meningioma patients experience tumor recurrence. Efforts have been made to improve the prognostic stratification of meningiomas. Recently, a multi-faceted molecular classification suggested that the marker S100 is associated with a favorable outcome, making a further analysis in a larger cohort interesting.

MATERIALS AND METHODS

The immunohistochemical staining for S100 was analyzed in 1669 paraffin-embedded meningioma samples. The distribution and association with clinical data and progression-free survival via radiographic tumor recurrence were assessed.

RESULTS

Of 1669 cases, 218 tumors showed strong S100 expression (13.1%). A significantly higher frequency of S100 positive meningiomas was observed in meningiomas of female patients, tumors with spinal and convexity/falx location, primary tumor surgery, NF2, higher extent of resection, lower WHO CNS grade, adjuvant radiotherapy and recurrence-free tumors during follow-up. Univariate analysis revealed a favorable progression-free survival for meningiomas with S100 expression (p = 0.0059) but not in the multivariate analysis. Higher S100 frequency was independently associated with female gender (p = 0.0003), NF2 (p < 0.0001), tumor location (p < 0.0001) and lower WHO CNS grade (p = 0.0133).

CONCLUSIONS

The positive prognostic impact of S100 is mostly attributed to the confounding clinical factors gender, tumor location, NF2 status and WHO CNS grade.

Synthesizing Molecular and Immune Characteristics to Move Beyond WHO Grade in Meningiomas: A Focused Review

No portion of this manuscript has previously been presented. Meningiomas, the most common primary intracranial tumors, are histologically categorized by the World Health Organization (WHO) grading system. While higher WHO grade is generally associated with poor clinical outcomes, a significant subset of grade I tumors recur or progress, indicating a need for more reliable models of meningioma behavior. Several groups have developed risk scores based on molecular or immunologic characteristics. These classification schemes show promise, with several models preliminarily demonstrating similar or superior accuracy to WHO grading. Improved understanding of immune system recognition and targeting of meningioma subtypes is necessary to advance the predictive power, as well as develop new therapies. Here, we characterize meningioma molecular drivers, predictive of recurrence and progression, and describe specific aspects of the immune response to meningiomas while highlighting critical questions and ongoing research. Relevant manuscripts of interest were identified using a systematic approach and synthesized into this focused review. Finally, we summarize the ongoing and completed clinical trials for immunotherapy in meningiomas and offer perspective on future directions.

Loss of H3K27me3 in WHO grade 3 meningioma

Immunohistochemical quantification of H3K27me3 was reported to distinguish meningioma patients with an unfavorable prognosis but is not yet established as a prognostic biomarker within WHO grade 3 meningiomas. We studied H3K27me3 loss in a series of biopsies from primary and secondary malignant meningioma to validate its prognostic performance and describe if loss of H3K27me3 occurs during malignant transformation. Two observers quantified H3K27me3 status as "complete loss", < 50% and > 50% stained cells in 110 tumor samples from a population-based consecutive cohort of 40 WHO grade 3 meningioma patients. We found no difference in overall survival (OS) in patients with > 50% H3K27me3 retention compared to < 50% in the cohort of patients with WHO grade 3 meningioma (Wald test p = 0.5). H3K27me3 staining showed heterogeneity in full section tumor slides while staining of the Barr body and peri-necrotic cells complicated quantification further. H3K27me3 expression differed without a discernible pattern between biopsies from repeated surgeries of meningioma recurrences. In conclusion, our results were not compatible with a systematic pattern of immunohistochemical H3K27me3 loss being associated with OS or malignant transformation of meningiomas and did not support H3K27me3 loss as a useful immunohistochemical biomarker within grade 3 meningiomas due to staining-specific challenges in quantification.

The Immunohistochemical Loss of H3K27me3 in Intracranial Meningiomas Predicts Shorter Progression-Free Survival after Stereotactic Radiosurgery

Simple Summary

In this study, we aimed to investigate whether the immunohistochemical expression of H3K27me3 in meningiomas might predict tumor progression after stereotactic radiosurgery (SRS) performed for residual or recurrent disease. In 39 intracranial meningiomas, H3K27me3 loss was significantly associated with tumor progression (p = 0.0143) and shorter PFS after SRS (p = 0.0036). These findings suggest that the loss of H3K27me3 in meningiomas may correlate to a weaker response to SRS.

Abstract

The immunohistochemical loss of histone H3 trimethylated in lysine 27 (H3K27me3) was recently shown to predict recurrence of meningiomas after surgery. However, its association with tumor progression after stereotactic radiosurgery (SRS) is unexplored. To investigate whether H3K27 methylation status may predict progression-free survival (PFS) after SRS, we assessed H3K27me3 immunoexpression in thirty-nine treatment naïve, intracranial, meningiomas, treated with surgery and subsequent SRS for residual (twenty-three cases) or recurrent (sixteen cases) disease. H3K27me3 immunostaining was lost in seven meningiomas, retained in twenty-seven and inconclusive in five. Six of the seven meningiomas (86%) with H3K27me3 loss had tumor progression after SRS, compared to nine of twenty-seven (33%) with H3K27me3 retention (p = 0.0143). In addition, patients harboring a meningioma with H3K27me3 loss had significantly shorter PFS after SRS (range: 10–81 months; median: 34 months), compared to patients featuring a meningioma with retained H3K27me3 (range: 9–143 months; median: 62 months) (p = 0.0036). Nonetheless, tumor sagittal location was the only significant prognostic variable at multivariate analysis for PFS after SRS (p = 0.0142). These findings suggest a previously unreported role of H3K27me3 as a predictor of meningioma progression after SRS for recurrent or residual disease. Modulation of H3K27 methylation status may represent a novel therapeutic strategy to induce radiosensitization of meningiomas.

Epigenetic Drugs and Their Immune Modulating Potential in Cancers

Epigenetic drugs are used for the clinical treatment of hematologic malignancies; however, their therapeutic potential in solid tumors is still under investigation. Current evidence suggests that epigenetic drugs may lead to antitumor immunity by increasing antigen presentation and may enhance the therapeutic effect of immune checkpoint inhibitors. Here, we highlight their impact on the tumor epigenome and discuss the recent evidence that epigenetic agents may optimize the immune microenvironment and promote antiviral response.

Neurooncology: 2022 update

This 'Neurooncology: 2022 update' presents topics that were selected by the authors as top ten discoveries published in 2021 in the broader field of neurooncological pathology. This time, the spectrum of topics includes: papers with a direct impact on daily diagnostic practice of CNS tumors in general and with information on how to improve grading of meningiomas; studies shedding new light on the oncogenesis of gliomas (in particular 'optic gliomas' and H3-mutant gliomas); several 'multi-omic' investigations unraveling the intra-tumoral heterogeneity of especially glioblastomas further; a study indicating the potential of 'repurposing' Prozac® for the treatment of glioblastomas; liquid biopsy using CSF for assessment of residual medulloblastoma. In the last part of this review some other papers are mentioned that didn't make it to this (quite subjective) top ten list.

Increased proliferation is associated with CNS invasion in meningiomas

INTRODUCTION

Meningiomas are the most common benign intracranial neoplasms. CNS invasion in meningiomas has been integrated into the 2016 WHO classification of CNS tumors as a stand-alone criterion for atypia. Since then, its prognostic impact has been debated based on contradictory results from retrospective analyses. The aim of the study was to elucidate whether histopathological evidence of CNS invasion is associated with increased proliferative potential.

METHODS

We have conducted a quantified measurement of the proliferation marker Ki67 and analyzed its association with CNS invasion determined by histology together with other established prognostic markers of progression. Routine, immunohistochemical staining for Ki67 were digitalized and automatic quantification was done using Image J software.

RESULTS

Overall, 1718 meningiomas were assessed. Histopathological CNS invasion was seen in 108 cases (6.7%). Uni- and multivariate analysis revealed a significantly higher Ki67 proliferation rate in meningiomas with CNS invasion (p < 0.0001 and p = 0.0098, respectively).

CONCLUSIONS

Meningiomas with histopathological CNS invasion show a higher proliferative activity.

Loss of H3K27me3 in meningiomas

BACKGROUND

There is a critical need for objective and reliable biomarkers of outcome in meningiomas beyond WHO classification. Loss of H3K27me3 has been reported as a prognostically unfavorable alteration in meningiomas. We sought to independently evaluate the reproducibility and prognostic value of H3K27me3 loss by immunohistochemistry (IHC) in a multicenter study.

METHODS

IHC staining for H3K27me3 and analyses of whole slides from 181 meningiomas across three centers was performed. Staining was analyzed by dichotomization into loss and retained immunoreactivity, and using a 3-tiered scoring system in 151 cases with clear staining. Associations of grouping with outcome were performed using Kaplan-Meier survival estimates.

RESULTS

A total of 21 of 151 tumors (13.9%) demonstrated complete loss of H3K27me3 staining in tumor with retained endothelial staining. Overall, loss of H3K27me3 portended a worse outcome with shorter times to recurrence in our cohort, particularly for WHO grade 2 tumors which were enriched in our study. There were no differences in recurrence-free survival (RFS) for WHO grade 3 patients with retained vs loss of H3K27me3. Scoring by a 3-tiered system did not add further insights into the prognostic value of this H3K27me3 loss. Overall, loss of H3K27me3 was not independently associated with RFS after controlling for WHO grade, extent of resection, sex, age, and recurrence status of tumor on multivariable Cox regression analysis.

CONCLUSIONS

Loss of H3K27me3 identifies a subset of WHO grade 2 and possibly WHO grade 1 meningiomas with increased recurrence risk. Pooled analyses of a larger cohort of samples with standardized reporting of clinical definitions and staining patterns are warranted.

Brain Invasion in Meningioma-A Prognostic Potential Worth Exploring

Most meningiomas are slow growing tumors arising from the arachnoid cap cells and can be cured by surgical resection or radiation therapy in selected cases. However, recurrent and aggressive cases are also quite common and challenging to treat due to no established treatment alternatives. Assessment of the risk of recurrence is therefore of utmost importance and several prognostic clinical and molecular markers have been established. Additionally, the identification of invasive growth of meningioma cells into CNS tissue was demonstrated to lead to a higher risk of recurrence and was therefore integrated into the WHO classification of CNS tumors. However, the evidence for its prognostic impact has been questioned in subsequent studies and its exclusion from the next WHO classification proposed. We were recently able to show the prognostic impact of CNS invasion in a large comprehensive retrospective meningioma cohort including other established prognostic factors. In this review we discuss the growing experiences that have been gained on this matter, with a focus on the currently nonuniform histopathological assessment, imaging characteristics and intraoperative sampling as well as the overall outlook on the future role of this potential prognostic factor.